This invention relates to a seat lock device for locking by stages in an inclined position a swingable member or a back rest of a seat rotatably supported on a pivotal shaft mounted on an immovable member.
The above-mentioned type of seat lock device has been used in the past. The prior art seat lock device comprises, for example, a ratchet and pawl positioned very close to the pivotal shaft about which the back rest of the seat is swung, and consequently is accompanied with the drawbacks that where the back rest of the seat is suddenly locked or is subjected to an external force, the seat lock device undergoes a great stress possibly to be damaged, making it necessary to construct said seat lock device with very great mechanical strength.
To eliminate the above-mentioned difficulties, another seat lock device has been devised which is designed to lock the swingable back rest of a seat at a point apart from the pivotal shaft of the seat. However, the proposed seat lock device has failed to meet a demand for a type of simple construction which enables the back rest of a seat to be inclined in a large number of stages. With, for example, a light van type automobile which is provided with a cargo section behind a rear seat, the back rest of the rear seat is made to swing back and forth. Hitherto, however, the back rest can take only two positions, that is, a slightly reclined normal position adapted for a rider to be seated thereon and a substantially horizontal forward thrown position to enlarge a cargo space. Therefore, the conventional seat lock device has the drawbacks that even where a required amount of cargo can be carried simply by locking the back rest of a rear seat in an upright position, the back rest has to be thrown forward in a substantially flat position due to the original design, preventing a rider to be seated on the rear seat. Further, where a small amount of cargo has only to be carried, the rider cannot be more comfortably seated on the rear seat by reclining the back rest thereof slightly backward from the normal position.